<!DOCTYPE html>
<html>

<head>
  <meta charset="utf-8">
  <title></title>
  <style media="screen">
    header,footer {height: 50px;background: lightgrey;}
    .wrapper {padding: 0 ; overflow:hidden;}
    .col {position: relative; float: left;}
    .main {width: 100%;height: 500px;background: dimgrey;}
    .left {width: 200px; height: 500px; background: pink;margin-left: -100%;}
    .right {width: 200px; height: 500px; background: orange;margin-left: -200px;}
  </style>
</head>

<body>
  <header>header</header>
  <section class="wrapper">
    <section class="col main">main</section>
    <aside class="col left">left</aside>
    <aside class="col right">right</aside>
  </section>
  <footer>footer</footer>
</body>

</html>
